1. Field of the Invention
The present invention relates to a power tool, in particular to a gun drill-type power tool capable of realizing storage of tool bits and quick replacement. The invention also relates to an operation method for said power tool.
2. Description of Related Art
The current gun drill type power tools usually include electric drills, electric screwdrivers and percussion drills.
The electric screwdriver is a common electric tool for fastening screws on workpieces. To fasten screws of different specifications, the tool bits shall be changed according to the specifications of the screws, which means the originally mounted tool bit shall be taken down and replaced by one with another structure. On occasions with the need for frequent replacement of tool bits, great inconvenience is brought to operators; on one hand, the replacement of the tool bits is inconvenient, and on other hand, the tool bits are easy to lose if not kept safely. Although, some of manual tools can realize storage and quick replacement of the tool bits, the inherent defects in the manual tools, namely small torque and difficulty in operation, usually makes the operator, cause low efficiency and therefore is unsuitable to be used as a professional tool in the industrial production.
A CN patent of utility model numbered CN201086280Y discloses a multi-bit electric tool which comprises an electric tool main body and a multi-bit rotating drum-like magazine structure, wherein the multi-bit rotating drum-like magazine structure comprises a drum-like magazine capable of receiving a plurality of tool bits; the drum-like magazine is capable of being connected with the tool main body in a axial sliding way; when the drum-like magazine slides to a position away from the tool main body, the required tool bit can be selected via the drum-like magazine. However, the number of the bits stored in the cylinder is limited, and it is inconvenient for replacement of other required bits by the operator.
Besides, when the drum-like magazine leaves the main body of the tool, the connecting shaft is exposed outside; dust and powder can enter the tool or the drum-like magazine when the drum-like magazine slides, and after a long time, the drum-like magazine will fail to rotate and select the bit or the electric tool cannot be used. During working, the tool bit is pressed against the workpiece, and the connecting shaft shall bear the action force in the reverse direction and apply pressure onto the transmission mechanism such that the transmission mechanism cannot transmit the torque to the connecting shaft. With such structure, the transmission of the electric multi-bit power tool is also not reliable.
Moreover, if the operator powers off the motor and manually rotates the bit, it is likely to trigger the bit that drives the connecting shaft to rotate so as to enable the motor to rotate. This may damage the motor. Failure to manual operation for fastening the screw brings great inconvenience to the operator.
When the bit is replaced, the bit shall be moved back to the drum-like magazine. To prevent the bit is absorbed by the magnet to leave the drum-like magazine when the drum-like magazine axially moves, the CN patent of utility model numbered CN201086280Y discloses an approach for preventing the bit from leaving the drum-like magazine by installing a fixed ring on the bit. However, this kind of bit shall be particularly customized, which limits the use of the tool. Moreover, it is unstable if the connecting shaft drives the bit to rotate because the longer connecting shaft shakes at a larger amplitude and causes some potential risks to the user of the tool. Furthermore, the drum-like magazine is required to axially move to be separated from the connecting shaft, so foreign matters such as dust can easily enter the drum-like magazine easily and are difficult to clean.
Due to the random movement of the electric tool in use, the angle of the cylinder wall of the connecting shaft for installing the tool bit is underdetermined, and the angle at which the tool bit moves back to the drum-like magazine is also underdetermined, so the angle of the cylinder wall of the connecting shaft and the angle of the tool bit may be staggered in the process of replacing the tool bit, which causes the situation that the tool bit cannot correctly and smoothly enter the connecting shaft. The CN patent of utility model numbered CN201086280Y also discloses linkage between the multi-bit drum-like magazine and the trigger. When the multi-bit drum-like magazine slides at a position away from the main body of the tool, the required tool bit can be selected by rotating the multi-bit drum-like magazine; when sliding back to the main body of the tool, the multi-bit drum-like magazine drives the linkage rod to move; the linkage rod contacts with and presses the trigger to power on the motor; and the motor rotate a certain angle such that the angle of the sleeve and the angle of the bit are matched. On one hand, regular short-time start of the motor usually reduces the service life of the motor or damages the motor; on the other hand, the linkage between the multi-bit drum-like magazine and the trigger requires precise location and control, which costs much.
Usually, the operator cannot observe the specific shape of the tool bit received in the drum-like magazine from the housing. To find the required tool bit, the operator needs to push or pull the tool bits for several times by the operating mechanism. The operations are inconvenient, so the working efficiency is low.